What is The Purpose of the Neutral Wire

The Purpose of the Neutral Wire in Electrical Systems: What is the purpose of the neutral wire and the difference between the ground wire and the white neutral wire.

The Neutral Wire in Electrical SystemsElectrical Question: What is the purpose of the neutral?

What is the difference between the green ground wire and the white negative wire?

These electrical questions came from: John, in Lemon Grove California, and John in Sun City Center, Florida.

Dave’s Reply:
Thanks for your electrical questions.

The Purpose of the Neutral Wire

The following will provide an explanation for the purpose of the neutral wire and the the difference between the ground wire and the neutral wire.

United States Home Electrical System
The typical home electrical systems here in the United States uses what is known as AC, which stands for Alternating Current.

120volt Circuits and the Neutral Wire
The typical 120volt AC circuit requires a return path to earth ground which is provided by the neutral. If the neutral wire were disconnected it would prevent the flow of electricity, therefore the circuit would stop working.

The Neutral Wire
The purpose of the neutral wire is to complete the 120volt AC circuit by providing the path back to the electrical panel where the neutral wire is connected and bonded to the earth ground. The neutral is an insulated wire because it is part of the circuit which flows electrical current.

The Grounded Electrode Conductor
The neutral wire is part of the GEC or Grounded Electrode Conductor which is part of the home electrical system. The connection of the neutral wire and the ground system is made only at the main electrical panel which is where the bond is made to the earth ground.

The Ground Wire is the Safety Wire
All 120 volt and 240 volt AC electrical circuits require a separate ground wire which also connects to the ground system of the panel where the circuit originates. The ground wire is not a part of the circuit current flow, therefore some ground wires are not insulated. The ground wire is the safety wire that is connected to the components of a circuit thereby providing a direct path to ground in the event of an electrical fault. Ground fault devices and other safety systems are required on specific circuits to prevent electrical shock in a fault condition. Over current devices such as fuses and circuit beakers are installed on circuits which react and interrupt the flow of electrical current in an abnormal condition.

NEC Code Requirements
The NEC, National Electrical Code, has several codes which must be considered for each specific electrical wiring project and application.

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The Safest Way to Test Electrical Devices and Identify Electric Wiring!

The Non-Contact Electrical Tester
This is a testing tool that I have had in my personal electrical tool pouch for years, and is the first test tool I grab to help identify electrical wiring. It is a Non-contact tester, [amazon.com], I use for the detection of Standard Voltage in Cables, Cords, Circuit Breakers, Lighting Fixtures, Switches, Outlets and Wires. Simply insert the end of the tester into an outlet, lamp socket, or hold the end of the tester against the wire you wish to test. Very handy and easy to use.

I am trying to connect a new cooktop. The cooktop has three wires, two are hot and one ground. I am connecting to a circuit cable with three conductors, with one ground wire. I know to connect the hot wires to the live conductors and the ground to the ground. I am not certain what to do with the neutral. The installation instructions say to connect the neutral to the ground wires. Is that correct?

I’m trying to understand the source and importance of the neutral wire. Assuming a storm knocks out the pole transformer which supplies electrical current to my house, if I use a generator to power my breaker panel, how does the neutral wire work?

Hi John,
It may help you to understand the relationship between the neutral and the ground system of the home. The function of the neutral wire can only work when the ground system is provided at the main panel. The only place the neutral wire is connected to the ground system is at the main power source, which is the main service panel where the ground system is bonded to the earth. Therefore the generator must also be grounded to the main electrical panel ground system. The connection of a generator to a home using a transfer switch must be performed properly to ensure the integrity of the complete electrical system.
Thank you for sharing your electrical question with us,
Dave

I need more room in my switch box. I currently have too many electric wire nuts on the wires in the box to allow full insertion of my switches. Can I crimp my hots and neutrals together then insulate with tape?

Hi Wayne,
Crimping electrical circuit wires is typically acceptable for the ground wires, however it is not a good practice for current carrying conductors. However you may want to choose a different type of wire splice connector for your application. Be aware that if the electrical box is over the allowed capacity of permissible electrical wires then it may be necessary to replace the box with a larger one which is deeper. If this is a surface mounted metal box then an extension ring may be stacked onto the face of the existing box, however the application would need to be considered.
Thanks for sharing your question with us Wayne,
Dave

if i put an open switch on the hot/live wire right before, say, a radio, no power goes to the radio. however, if i put an open switch on the neutral wire right after the radio, the radio will be full of power. so what is the purpose of a return, neutral wire?

could i just then have 1 hot/live wire and a ground wire coming out of it?

also, if AC goes back and forth, does the neutral become hot/live and the hot/live become neutral on the second half of the cycle?

Thank you both for your article, question and website. I have been learning about electricity for at least 30 years and the more I see, the more I know there is yet to figure out. It has been my understanding that the grounded or “neutral” conductor provides a path back to the source, that is the transformer and not to the earth/ground. This is how the circuit is ultimately completed or closed. Please correct me if I am wrong or let me know if this has been helpful.

Hi Thomas, Great Thoughts!
Here’s something that may help you: If you take a look at a typical electrical overhead power line that provides 240 volt service to a home you will notice that there are only two wires on the primary or secondary side of the power pole which either connects directly to the home service or to a step down transformer. So where is the neutral wire?
The service drop from the home to the power pole has three wires, however one is uninsulated because it is the ground conductor. The electrical service to the home from the utility company does not have a neutral wire, however it does have a ground conductor. The neutral is created at the home main electrical panel where it is bonded to the earth ground.
NOTE: In some areas an electric utility transformer may supply power to more than one home. In this case three wires will lead out from the transformer to each home electrical service connection.
I will develop more resources that cover this topic further because there is a great deal of confusion about Alternating Current, especially when discussing the topics of a 120 volt AC circuit, and alternating current which is produced by a multi-phase generator.
I hope this helps,
Dave